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Sun haven't enough temperature to break down coulomb barrier between two protons to be fussed.But yet nuclear fusion occurs through quantum tunnelling process.So,why we can't use quantum tunnelling in our nuclear fusion technology same as sun do still now?

Abu sayed
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    We are trying to do the equivalent of what the sun does in billions of year (to fuse a few percent of its hydrogen) in hours (reactor) or microseconds (bombs) with our DT fuel. Having said that, I don't know if one can rule out tunneling reactions in either reactors or bombs. My feeling is that at least some fraction of the reactions go trough a narrow tunneling window. – CuriousOne Jul 10 '16 at 06:50

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Here is what tunneling is about, simplified:

tunneling

According to classical physics, a particle of energy E less than the height U0 of a barrier could not penetrate - the region inside the barrier is classically forbidden. But the wavefunction associated with a free particle must be continuous at the barrier and will show an exponential decay inside the barrier. The wavefunction must also be continuous on the far side of the barrier, so there is a finite probability that the particle will tunnel through the barrier.

As a particle approaches the barrier, it is described by a free particle wavefunction. When it reaches the barrier, it must satisfy the Schrodinger equation in the form .

This is a very simple picture of a free particle approaching a barrier, and nuclei are strong potential wells, so the wavefunctions have to be calculated or at least estimated. Yes, theorists have done the calculations:

For example here

arXiv:nucl-th/9708036v1 19 Aug 1997 Quantum Tunneling in Nuclear Fusion

where the theory is developed in chapter:

III MULTIDIMENSIONAL QUANTUM TUNNELING IN NUCLEAR PHYSICS

Actually three different calculations are offered.

So the answer is that tunneling calculations are used for fusion processes.

anna v
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  • Do you happen to now if there is a significant contribution of tunneling to fusion cross sections in fusion experiments or hydrogen bombs? – CuriousOne Jul 10 '16 at 21:36
  • @CuriousOne I found this for example http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.39.88 . After all is modelling. – anna v Jul 11 '16 at 02:42
  • @CuriousOne also look for "tunnel" here http://mafija.fmf.uni-lj.si/seminar/files/2011_2012/Fusion.pdf . You made me curious :) – anna v Jul 11 '16 at 03:00
  • Yeah... maybe it's trivial to exclude, but I just can't come up with a simple argument. – CuriousOne Jul 11 '16 at 03:08